Joint production of plurality of good oil fractions from mineral oil



April 13, 1937. M. H. TUTTLE JOINT PRODUCTION OF PLURALITY OF GOOD OILFNAOTIONS FROM MINERAL OIL Filed oct. 23, 1934 ATTORNEYS.

Patented Apr. 13, 1931 UNI-TED STATES musi PATE-NT OFFICE Malcolm n. Tuttle, New nonnen, N. Y., uam' to Max B. Miller t Co., Inc., New York, N. Y., a corporation of Delaware v Y Application October 2S, V1934, Serial N0. 749,519

4 Claims. (CL 19E-13) This invention relates to the solvent extraction of mineral oils and more particularly to improved process and apparatus for separating such oils into a naphthenic type or tar fraction and 5 into one or more paraillnic type or lubricating oil fractions, the solvents being, recovered therefrom for reuse in the process.

For a statement of the general principles of solvent extraction of mineral oils reference may be had to my Patent 1,912,349 issued May 30, 1933. For a detailed description of a form of apparatus which4 is well adapted for carrying out the patentedA process reference may be had to my copending application Ser. No. 698,746 filed November 20, 1933. Such an apparatus will be in part redescribed herein, but it will be understood that the details thereof form no part of the present invention, at least in its broader aspects.

However, whether the appratus is constructed in accordance with these details or not, it includes'generally stated, two principal portions: first, extraction apparatus and second, solvent recovery apparatus. Now, when a batch of high grade lubricating oil is to be produced, given quantities of solvents are preferably employed,

and the solvent recovery apparatus is advantageously designed and built for economic recovery of such amounts of solvents. 0n the other hand, when a batch of lower grade lubricating oil is to be produced, very dierent amounts of one or both solvents are used, so that the recovery apparatus functions uneconomically if it has been designed and built for handling different quantities of solvents. Large reneries today entail tremendous capital investments, and additional equipment for diiferent grades of product is to be avoided.

A feature of the present invention hence resides in the provision of an improved process of 40 and apparatus for producing different grades of lubricating oil without lincurring the disadvantages mentioned.

More specifically, a feature of the invention involves process and/or apparatus for jointly producingfrom a single charging stock one or more grades of good oil in an economic manner.

Other features, objects and advantages will become apparent in connection with the following detailed description of an example in accordance with the invention, reference being had to th accompanying. drawing.

Referring to the drawing, there is shown diagrammatically a form of apparatus constructed in accordance with the principles of the invention, and which involves a number of advantages from the standpomts of both simplicity and emcient operation. This form of apparatus may include an extractor tank 49 subdivided by partitions 4I into a plurality of similar, generally horizontal extracting and settling chambers or pots 43-5I, inclusive. Provision is preferably made for introducing solvents into the end chambers 48 and 5I and for introducing an oil to be treated into a chamber 43 intermediate the end chambers. For instance, a solvent for paramnic oil, such as liquefied propane or other satisfactory solvent, which may be'introduced through pipe. 52 into chamber 49, while a solvent for the naphthenic oil, such as cresylic acid or other satisfactory solvent, which is immisclble with the upper layer from chamber 44 is fed by pipe 1ine B6, the operations being/preferably continuo'us. 'lhese layers contain amounts oi' parailinic and naphthenic solventaas well as'dis.

solved constituents. The mixture is then introduced into the chamber 43 near one end thereof and is allowed to flow toward the-other end of the chamber, while stratifying or settling into layers. the construction being such that with a given rate of ilow, the settling into layers has ample opportunity to take place to the desired extent, or, in other words, so that the turbulent condition of the mixture at the point of inlet is sumciently reduced to permit withdrawal of separate layers at points spaced from the inlet.

The lower layer may be withdrawn from the chamber by a pump (not shown) and may be introduced to the chamber 44 through a line Il, in mixture with the upperl layer from chamber 45, the mixing being accomplished by another mixing device 58 connected with the chamber 44. The upper layer from chamber 43 may be withdrawn from a suitable point above the bottom of the chamber by line 68, added to a lower layer from chamber 48 and passed into chamber 41 through a mixing'device 58 connected with this chamber.

'I'he chambers 44-4f4constitute a series of similar chambers which may be termed preceding chambers, and in which the lower or naphthenic layer from the initial separation of the oil is successively treated by paraftlnic solvent introduced into chamber 46 and advanced in countercurrent flow to meet the lower layer from chamber 43. That is to say, the lower layer from chamber 43 is relatively rich in naphthenic constituents, and this layer is treated with solvent for paraiilnic oil, the apparatus being constructed so that the paraiiinic solvent is richestvor freshest in the iinal stage of the treatment of naphthenic oil, while initially the oil is ,contacted with solvent which has already taken up considerable parafstood that the number of chambers may be varied,

or that a layer-may be` passed into a chamber further along than the one next to the chamber from which the layer is withdrawn.

The upper or paraillnic layer from end chamber A 5| is withdrawn through back pressure valve 60 and pipe 6| and the lower layer from chamber 46 y is withdrawn from near the bottom of this chamber through valve 62 and pipe 63.

The present apparatus is adapted for handling a normally gaseous solvent, such as propane, and maintaining it in a liquid state. Adequate pressure may be maintained, for instance, by pumping the oil and solvents into the system under pressure and limiting the withdrawal of the paraiiinic and naphthenic layers to such a rate as to maintain the desired pressure. 'I'he extraction apparatus is preferably maintained full of liquid by suitable valves, pumps and other contrivances. Preferably, an equilibrium is established between the solvents and dissolved constituents in each chamber, aided by recirculation where desired.

Itis generally desirable to free the raffinate and extract layers of solvents by evaporating or distilling the same from these layers. For this purpose, the raiiinate layer may be sent to any suitable evaportor 10 for evaporating propane or other paraiilnic solvent. The balance of the raiinate, containing some naphthenic solvent, may be sent to a suitable evaporator 1 I, where the naphthenic solvent is distilled and recovered for return to the system through line 53. Similarly, the extract layer may be passed through parafflnic solvent evaporator 12 and naphthenic solvent evaporator 13, the solvents being recovered and returned to the system as indicated in the drawing.

It will be appreciated that the solvent recovery system is complementary to the extraction system, and that the former is preferably designed for handling particular quantities of solvents, preferably the maximum amounts required for the production of the high grade paramnic oil which it is desired to produce in the apparatus.

In accordance with the present invention, another grade of lubricating oil may be produced from the same charging stock, without reconstruction of the major portion of the apparatus, by removing from a suitable point in the extraction apparatus a portion of a paraflniclayer. For instance, such a portion may advantageously be removed between the point where the charge oil is introduced and the point where the most paramnic ramnate is removed. By Way 0f example, a portion of the upper layer may be removed from chamber 48 through valve 30, line 3| and constant flow controller 32. By means of the constant ow controller, a predetermined ratio can be established and maintained between the quantity of second grade oil produced and the quantity oi' the paraillnlc raiilnate removed from chamber BI. It will be understood that the second grade oil fraction thus-removed may be stored in a suitable tank and hatched through the solvent recovery apparatus 10', 1| between batches of most parailinic railinate In this manner not only may a variety of grades of oil be produced in the sameapparatus, but the solvent recovery portion of the apparatus is enabled to operate at full efficiency. In addition, the most parailinic ramnate is extracted with fresh naphthenic solvent just before it leaves the extraction system, while the second grade oil is extracted with naphthenic solvent which already contains dissolved constituents. Economical use of solvent is thus achieved.

If a third grade oil, or one poorer in quality than the second grade oil, th'ough superior to the charging stock, is to be produced, it may be withdrawn, -for instance from extraction chamber 44 through valve 20 and line 2|, the rate o1' withdrawal being'controlled by a constant flow controller 22. It will be understood that whatever oil is not withdrawn as second or third grade oil, will continue to ilow through the system and be improved in quality until withdrawn as paraillnic raiinate. It is therefore possible, by virtue of the present development, to change over from the production oi' a. single grade of oil to the production of two, or even more grades of oil from a given charging stock.

Merely by way of example, if the charge oil is a Mid-continent residual, topped stock of average characteristics, there may be produced in accordance with the present process a high grade parailnic type oil having a Saybolt viscosity of 140 at `100 F., a viscosity index oi 100, and a carbon residue of less than 0.6, and a second grade oil having a viscosity index of -85 and a carbon residue of less than 2.0, when about 300 pounds of liquefied propane per pounds of charging stock, and 200 pounds of cresylic acid per 100 pounds of stock are introduced to the extraction system as indicated, and when the quantity of raffinate withdrawn through line 6| is about equal to the amount of the fraction withdrawn through line 3|, although this ratio may vary according to the quantity of each product desired. It will be understood that several different types of oils may be simultaneously produced, if desired.

By operation as vabove described, a plurality of grades of oil may be produced simultaneously with evaporation equipment operating at full load. Furthermore, a higher viscosity oil can be produced at a. higher tar concentration because of the use of naphthenic solvent for finishing the higher grade railinate before it is used -for extraction of mixed stocks. All the extract is washed with paraiiinic solvent at a high ratio of parainic solvent to naphthenic solvent, but the removal of part of the upper layer before the nal extraction of the paralllnic raiilnate permits a. high ratio of naphthenic solvent to paramnic solvent and a high ratio of vnaphthenic solvent to paramnic oil at this end of the system. Moreover, a continuous operation, of the solvent extraction apparatus is made possible.

The terms and expressions which have been employed are used as terms of description and not oi limitation, and there is no intention, in the use of such terms and expressions, of excluding any equivalents of the features shown and described, or portions thereof, but it is recognized that various modifications are possible within the scope of the invention claimed.

I claim:

1, A process for extracting a mineral oil by means of counterowing separable, paraflinic and naphthenic solvents, which comprises continuously counterfiowing said solvents by introducing them at spaced points, continuously introducing mineral oil to be treated to said counterflowing solvents at an intermediate point, continuously withdrawing extract and raffinate fractions from points respectively adjacent said first-named points, evaporating said solvents from said rafnate and extract fractions in suitable evaporators, withdrawing an intermediate raflinate fraction at a point between the point Where the first-named rafnate is withdrawn and the point of introducing charge oil, and evaporating the solvents from said intermediate raffinate by batches in the same evaporating system employed for freeing the first-named parafnic rafiinate from solvents.

2. A process for extracting a mineral oil by means of counterilowing separable paraillnic and naphthenic solvents which comprises continuously counterfiowing said solvents by introducing them at spaced points, continuously introducing mineral oil to be treated to said counterowing solvents at a point spaced from the point of inl troduction of naphthenic solvent, continuously withdrawing a parainic railinate fraction from a point adjacent the point of introduction of said naphthenic solvent, continuously withdrawing a naphthenic extract fraction from a point on the opposite side of the point of introduction of the said raiiinate, evaporating said solvents from said rafnate fraction in suitable evaporators, withdrawing an intermediate raiiinate fraction at a point between the point where the first-named raflinate is withdrawn and the point of introducing mineral oil to be treated, and evaporating the solvents from said intermediate rainate in the same evaporating system employed for freeing the first-named paraflinic raffinate from solvents, said intermediate and first-named raflinates being separately hatched through said evaporating system.

3. Process as claimed in claim 1, wherein intermediate fraction is withdrawn from a point between the point of introduction of charge oil to be treated and the point of introduction of the paraflinic solvent, and wherein said fraction so withdrawn is treated for removal of both parafnic and naphthenic solvents.

4. The process of extracting a mineral oil by means of counterfiowing parainic and naphthenic solvents, in which process said solvents are introduced at spaced points, while the mineral oil to be treated is introduced at a point intermediate said points, and in which process a most parailnic fraction is withdrawn adjacent the point of introducing the naphthenic solvent, and a most naphthenic fraction is withdrawn at a point adjacent the point of introducing paraillnic solvent, the steps comprising withdrawing, from between the point of introduction of the mineral oil to be treated and the point of withdrawal of the most paraflinic fraction, an intermediate oil fraction which is more parafiinic than said mineral oil, and less paraflnic than the oil withdrawn adjacent the point of introduction of naphthenic solvent, and separating both parafnic and naphthenic solvents from said intermediate withdrawn oil fraction to produce a final product.

MALCOLM H. TU'II'LE. 

